With the development of the motor system energy-saving engineering, the demand for high-efficient and energy-saving motor is gradually increased. Moreover, a motor that is specific to a certain industry and can be applied under different load characteristics is needed to be designed. Textile industry consumes large amounts of electric energy, so developing textile-manufacturing-dedicated and high-efficient motor is especially important. Nowadays, asynchronous motor has taken major share in the textile-manufacturing-dedicated motors, and it has quite matured design and production techniques. Therefore, for a lower startup cost, people are focus on researching and developing a textile-manufacturing-dedicated, high-efficient, energy-saving, multiphase asynchronous motor, which has wider application range, more profit and larger development in specific industries.
The design of the textile-manufacturing-dedicated motor is different from the design of the normal AC motor due to its special operation mode. On the one hand, considering the energy saving, the textile-manufacturing-dedicated motor requires higher operation efficiency and power factor to decrease the loss caused by reactive power transmission and reduce the investment of the reactive power equipment. On the other hand, although the textile-manufacturing-dedicated motors are designed according to the rated operating point, they are normally operating under unrated operating point in the actual operation due to the particularity of the work. Thus, the efficiency of the motor should be higher not only at the rated operating point but also in the wider operating range, so that the motor can be guaranteed to be high-efficient and energy-saving in the actual work.
The motor is a complicated coupling system whose various performances influence each other and constraint each other. To design a motor, various factors, such as operating efficiency, production cost, volume, should be comprehensively considered, as well as complicated constraints in the motor, such as electromagnetic load, overload capacity, torque characteristic, mechanical structure, ventilation and heat of the machine are still needed to be taken into account. Furthermore, the motor performance indexes is sensitive to the variation of the design parameter. Under the influence of the quality management such as business process control and production flow, the motor performances become declined at different levels and exist a certain number of discrete degree, thus it is difficult to guarantee the performance of large-scaled production of motor is consistent. Therefore, providing a robust design method for the motor that can meet the state standards, users requirements and specific constraints, which can make the comprehensive performance of the motor optimal, has vital influence on solving the conflicts among the motor performance indexes, and guaranteeing the high-efficient operation of the motor.
Traditional quality management method focuses on the later inspection after production, which wastes time and resources and lacks effective control for preventing non-conforming products. Moreover, the empirical process control lacks scientific design guide and is difficult to satisfy the demand for the products consistency of large-scaled production of motors. In 1970s, Taguchi method which is a robust design method and quality management technology is developed by Dr. Taguchi Genichi to pursue the optimal quality of products. Taguchi method employs reasonable experimental schemes to determine the optimal combinations of parameters. Then, the robustness of the products' quality characteristics against various disturbances is enhanced, and the optimal balance between the quality and cost is finally realized. Taguchi method divides the whole design process into three stages: system design, parameter design and tolerance design, so it is also called as three stages designs. And this method has achieved remarkable results in the research and production fields.